U.S. patent application number 12/879680 was filed with the patent office on 2011-03-31 for multilayer coil device.
This patent application is currently assigned to MURATA MANUFACTURING CO., LTD.. Invention is credited to Yoshiko BANNO.
Application Number | 20110074535 12/879680 |
Document ID | / |
Family ID | 43779662 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110074535 |
Kind Code |
A1 |
BANNO; Yoshiko |
March 31, 2011 |
MULTILAYER COIL DEVICE
Abstract
A multilayer coil device is formed by alternately stacking a
plurality of insulating layers and a plurality of substantially
spiral coil patterns. In the multilayer coil device, the number of
turns of each of the substantially spiral coil patterns is more
than one. Each of the substantially spiral coil patterns has a
protrusion protruding toward a center of the substantially spiral
coil pattern. The protrusion is located in a specific region where
the number of coil pattern portions that cross a virtual line
extending radially outward from the center of the coil pattern is
smaller than that in another region of the substantially spiral
coil pattern. The protrusion is provided as an additional part of a
coil pattern portion that is closest to the center of the
substantially spiral coil pattern in the specific region.
Inventors: |
BANNO; Yoshiko; (Kyoto-fu,
JP) |
Assignee: |
MURATA MANUFACTURING CO.,
LTD.
Kyoto-fu
JP
|
Family ID: |
43779662 |
Appl. No.: |
12/879680 |
Filed: |
September 10, 2010 |
Current U.S.
Class: |
336/192 ;
336/200 |
Current CPC
Class: |
H01F 17/0013 20130101;
H01F 27/292 20130101 |
Class at
Publication: |
336/192 ;
336/200 |
International
Class: |
H01F 27/29 20060101
H01F027/29; H01F 5/00 20060101 H01F005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2009 |
JP |
2009-224882 |
Claims
1. A multilayer coil device comprising: a multilayer body including
a plurality of insulating layers, a coil part composed of a
plurality of substantially spiral coil patterns, and a pair of
extraction electrodes connected to both ends of the coil part, the
multilayer body being formed by alternately stacking the insulating
layers and the coil patterns; and a pair of external electrodes
formed on both end faces of the multilayer body and electrically
connected to the respective extraction electrodes, wherein the
number of turns of each of the substantially spiral coil patterns
is more than one; and each of the substantially spiral coil
patterns has a protrusion located in a specific region of the
substantially spiral coil pattern where a number of coil pattern
portions of the substantially spiral coil pattern that cross a
virtual line extending radially outward from a center of the coil
pattern is smaller than that in another region of the substantially
spiral coil pattern, the protrusion being provided as an additional
part of a specific coil pattern portion that is closest to the
center of the substantially spiral coil pattern in the specific
region, the protrusion protruding toward the center of the
substantially spiral coil pattern such that a line width of the
specific coil pattern portion is larger than that of other coil
pattern portions in the other region of the substantially spiral
coil pattern.
2. The multilayer coil device of claim 1, wherein each said
substantially spiral coil pattern has an inside diameter area
having a substantially polygonal shape with a periphery defined in
part by the protrusion.
3. The multilayer coil device of claim 1, wherein each
substantially spiral coil pattern has an end portion connected to
an end portion of another substantially spiral coil pattern, said
end portion provided adjacent to a side portion of the protrusion
that does not face the center of the substantially spiral coil
pattern.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to Japanese Patent
Application No. 2009-224882, which was filed on Sep. 29, 2009, the
entire contents of which is incorporated herein by reference in
their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to multilayer coil devices
formed by alternately stacking insulating layers and substantially
spiral coil patterns. In particular, the present invention relates
to multilayer coil devices, such as multilayer power inductors,
multilayer common-mode choke coils, and high-frequency multilayer
inductors.
BACKGROUND
[0003] Examples of multilayer coil devices of the above-described
type include a multilayer inductor described in Japanese Unexamined
Patent Application Publication No. 2005-109097. This multilayer
inductor is formed by alternately stacking insulating layers and
substantially spiral coil patterns. With the multilayered coil
patterns having multiple turns, this multilayer inductor achieves
higher inductance.
[0004] However, in the multilayer inductor described above, the
higher inductance results in a longer coil length, which may lead
to increased direct-current resistance.
[0005] If the line width of the entire coil patterns is increased
to reduce the direct-current resistance, the following problems may
arise.
[0006] In a multilayer inductor, such as that illustrated in FIG. 4
and FIG. 5, increasing the line width of coil patterns reduces an
inside diameter area S of a coil part and a width of a side gap G.
This may reduce an inductance value or cause deterioration of
direct-current superimposition characteristics.
[0007] Additionally, since the coil patterns are substantially
spiral in shape, if, for example, a sheet lamination technique is
used as a production method, the coil patterns may be deformed by
smearing during screen printing or by pressure applied thereto
during stamping. This may cause short circuits between lines of the
coil patterns.
SUMMARY
[0008] The present invention is directed to a multilayer coil
device that addresses the problems described above, and can achieve
lower direct-current resistance.
[0009] A multilayer coil device consistent with the claimed
invention includes a multilayer body and a pair of external
electrodes.
[0010] The multilayer body includes a plurality of insulating
layers, a coil part composed of a plurality of substantially spiral
coil patterns, and a pair of extraction electrodes connected to
both ends of the coil part. The multilayer body is formed by
alternately stacking the insulating layers and the coil
patterns.
[0011] The external electrodes are formed on both end faces of the
multilayer body and electrically connected to the respective
extraction electrodes.
[0012] In the multilayer coil device, the number of turns of each
of the coil patterns is more than one. Each of the substantially
spiral coil patterns has a protrusion located in a specific region
where a number of coil pattern portions that cross a virtual line
extending radially outward from a center of the coil pattern is
smaller than that in another region of the substantially spiral
coil patter. The protrusion is provided as an additional part of a
specific coil pattern portion that is closest to the center of the
substantially spiral coil pattern in the specific region. The
protrusion protrudes toward the center of the coil pattern such
that a line width of the specific coil pattern portion is larger
than that of other coil pattern portions in the other region of the
substantially spiral coil pattern.
[0013] With the present invention, where it is not necessary to
change the line width of the entire coil patterns, an inside
diameter area of the coil part and a width of a side gap can be
maintained. Therefore, with the present invention, it is possible
to reduce direct-current resistance while maintaining an inductance
value of the coil part and the performance of direct-current
superimposition characteristics.
[0014] Additionally, even when a sheet lamination technique is used
as a production method, it is possible to prevent short circuits
between lines of the coil patterns.
[0015] Other features, elements, characteristics and advantages of
the present invention will become more apparent from the following
detailed description of preferred embodiments of the present
invention with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is an exploded perspective view of a multilayer coil
device according to an exemplary embodiment.
[0017] FIG. 2 is a plan view of a coil pattern on an insulating
layer according to the embodiment shown in FIG. 1.
[0018] FIGS. 3A to FIG. 3D are plan views illustrating exemplary
modifications of a coil pattern.
[0019] FIG. 4 is an exploded perspective view of a known multilayer
coil device.
[0020] FIG. 5 is a plan view of a coil pattern on an insulating
layer of the known multilayer coil device.
DETAILED DESCRIPTION
[0021] Exemplary embodiments of a multilayer coil device will now
be described.
[0022] FIG. 1 is an exploded perspective view of a multilayer coil
device according to an exemplary embodiment (first embodiment) of
the present invention.
[0023] As illustrated in FIG. 1, a multilayer coil device 1 of the
first embodiment includes a multilayer body 2 and a pair of
external electrodes 3-1 and 3-2.
[0024] The multilayer body 2 is formed by alternately stacking
insulating layers 41 to 45 and electrically conductive coil
patterns 51 to 54.
[0025] More specifically, the coil pattern 51 and an extraction
electrode 61 are disposed on the insulating layer 41 at the bottom.
The insulating layer 42 is disposed on the coil pattern 51 and the
extraction electrode 61, and the coil pattern 52 is disposed on the
insulating layer 42. The insulating layer 43, the coil pattern 53,
the insulating layer 44, the coil pattern 54, and an extraction
electrode 62 are sequentially provided, or disposed on the coil
pattern 52. Then, the insulating layer 45 is provided on top of
them to form the multilayer body 2.
[0026] An end portion 51b of the coil pattern 51 and an end portion
52a of the coil pattern 52, an end portion 52b of the coil pattern
52 and an end portion 53a of the coil pattern 53, and an end
portion 53b of the coil pattern 53 and an end portion 54a of the
coil pattern 54 are electrically connected to each other through
respective through holes (not shown) in the insulating layers 42,
43, and 44. Thus, a substantially spiral multilayered coil part
with multiple turns can be obtained.
[0027] The coil patterns 51 and 54 are electrically connected to
the extraction electrodes 61 and 62, respectively. The extraction
electrodes 61 and 62 are electrically connected to the external
electrodes 3-1 and 3-2, respectively.
[0028] The coil patterns 51 to 54 of the first embodiment have coil
pattern protrusions 71 to 74, respectively.
[0029] The coil pattern protrusions 71 to 74 will be described in
detail with reference to FIG. 2.
[0030] FIG. 2 is a plan view of the coil pattern 52 on the
insulating layer 42 according to the first exemplary
embodiment.
[0031] The coil pattern 52 on the insulating layer 42 is a
substantially spiral pattern with about one and seven-eighths
turns.
[0032] The coil pattern 52 has the coil pattern protrusion 72.
[0033] The coil pattern protrusion 72 is located in a specific
region of the spiral coil pattern 52 where the number of coil
pattern portions that cross a virtual line extending radially
outward from a center of the substantially spiral coil pattern 52
is smaller than that in another region of the spiral coil pattern
52. The coil pattern protrusion 72 is provided as an additional
part of a specific coil pattern portion that is closest to the
center of the coil pattern 52 in the specific region.
[0034] Since the coil pattern protrusion 72 protrudes toward the
center of the substantially spiral coil pattern 52, the line width
of this specific coil pattern portion is larger than that of the
other coil pattern portions in the coil pattern 52.
[0035] In the first exemplary embodiment, the multilayer coil
device 1 has a substantially spiral coil part formed by stacking
substantially double spiral coil patterns. In this structure, in a
region where the number of coil pattern portions that cross a
virtual line extending radially outward from a center of a
substantially spiral coil pattern is smaller than that in the other
region, an area inside a coil pattern portion that is closest to
the center of the coil pattern is a dead space.
[0036] More specifically, as viewed from the top surface of the
multilayer body 2 (i.e., as viewed from above the insulating layer
45 of FIG. 1) through the coil patterns 51, 52, 53, and 54, an
inside diameter area of the coil part corresponds to, for example,
an inside diameter area S illustrated in FIG. 2. This area
determines an inductance value and performance of direct-current
superimposition characteristics of the multilayer coil device 1 of
the present invention. In contrast, a dead space, such as that
described above, has less impact on the inductance value and the
performance of direct-current superimposition characteristics.
[0037] Since a coil pattern protrusion, such as that described
above, is provided in the dead space, it is possible in the present
invention to reduce the direct-current resistance of the entire
coil part. Even with the coil pattern protrusion, it is still
possible to maintain the inductance value and the direct-current
superimposition characteristics of the coil part.
[0038] In the first embodiment described above, the spiral of each
of the coil patterns 51 to 54 has more than one turn, more
specifically, about one and seven-eighths turns. However, the coil
pattern 52 can be a coil pattern with a different number of turns,
for example, about two and seven-eighths turns, about three and
seven-eighths turns, about one and a half turns, or about one and
three-fourths turns, as illustrated in FIG. 3A, FIG. 3B, FIG. 3C,
and FIG. 3D, respectively. In each of these exemplary cases, the
coil pattern 52 has the coil pattern protrusion 72 as illustrated
in the drawings.
[0039] While the above description discusses exemplary coil pattern
protrusions 72 of respective exemplary coil patterns 52 on the
insulating layer 42, the same can apply to the coil pattern
protrusions 71, 73, and 74 of the coil patterns 51, 53, and 54,
respectively.
[0040] While preferred embodiments of the invention have been
described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the invention. The scope of
the invention, therefore, is to be determined solely by the
following claims and their equivalents.
* * * * *